Function establishTunnel

lib/https.js:213–321

(agent, socket, options, tunnelConfig, afterSocket)

};

function establishTunnel(agent, socket, options, tunnelConfig, afterSocket) {
  const { proxyTunnelPayload } = tunnelConfig;
  // By default, the socket is in paused mode. Read to look for the 200
  // connection established response.
  function read() {
    let chunk;
    while ((chunk = socket.read()) !== null) {
      if (onProxyData(chunk) !== -1) {
        break;
      }
    }
    socket.on('readable', read);
  }

  function cleanup() {
    socket.removeListener('end', onProxyEnd);
    socket.removeListener('error', onProxyError);
    socket.removeListener('readable', read);
    socket.setTimeout(0);  // Clear the timeout for the tunnel establishment.
  }

  function onProxyError(err) {
    debug('onProxyError', err);
    cleanup();
    afterSocket(err, socket);
  }

  // Read the headers from the chunks and check for the status code. If it fails we
  // clean up the socket and return an error. Otherwise we establish the tunnel.
  let buffer = '';
  function onProxyData(chunk) {
    const str = chunk.toString();
    debug('onProxyData', str);
    buffer += str;
    const headerEndIndex = buffer.indexOf('\r\n\r\n');
    if (headerEndIndex === -1) return headerEndIndex;
    const statusLine = buffer.substring(0, buffer.indexOf('\r\n'));
    const statusCode = statusLine.split(' ')[1];
    if (statusCode !== '200') {
      debug(`onProxyData receives ${statusCode}, cleaning up`);
      cleanup();
      const targetHost = proxyTunnelPayload.split('\r')[0].split(' ')[1];
      const message = `Failed to establish tunnel to ${targetHost} via ${agent[kProxyConfig].href}: ${statusLine}`;
      const err = new ERR_PROXY_TUNNEL(message);
      err.statusCode = NumberParseInt(statusCode);
      afterSocket(err, socket);
    } else {
      // https://datatracker.ietf.org/doc/html/rfc9110#CONNECT
      // RFC 9110 says that it can be 2xx but in the real world, proxy clients generally only
      // accepts 200.
      // Proxy servers are not supposed to send anything after the headers - the payload must be
      // be empty. So after this point we will proceed with the tunnel e.g. starting TLS handshake.
      debug('onProxyData receives 200, establishing tunnel');
      cleanup();

      // Reuse the tunneled socket to perform the TLS handshake with the endpoint,
      // then send the request.
      const { requestOptions } = tunnelConfig;